Wind turbines are receiving increased attention as an environmentally safe and relatively inexpensive alternative energy source. With this growing interest, considerable efforts have been made to develop wind turbines and wind turbine plants that are reliable, efficient, and cost-effective.
Placement of wind turbines within a wind power plant has traditionally been performed with the single objective of maximizing overall energy production from the plant. For example, in designing the wind plant, wind turbines are initially placed at locations within the geographic boundaries of the plant having the highest winds based on a wind resource grid. A wind resource grid can be generated using commercially available wind resource assessment or modeling software such as WindPro™ (available from EMD International A/S, Aalborg, Denmark), WindFarmer™ (available from Garrad Hassan, Bristol United Kingdom), or WindFarm™ (available form ReSoft Ltd., Banbury, United Kingdom). Other design criteria or constraints, such as exclusion zones, minimum spacing constraints, noise restrictions, and the like, are then used to adjust the turbine layout.
Other wind plant design objectives, such as minimizing the cost of the wind plant, maximizing financial metrics, and minimizing noise, may also be taken into account in designing the plant layout. Various commercial software programs may be helpful in this regard. For example, to address cost, financial metrics, and noise constraints, software such as WindPro™, WindFarmer™, or WindFarm™ offer analysis modules that can be used to manually adjust the turbine layout as desired. In addition, these programs may offer a function or module allowing for the automatic maximization of energy production for a fixed number of wind turbines and a particular wind turbine model/configuration. Noise constraints and exclusion zones may also be considered in these programs. Even with the available software programs, additional analysis is needed before the turbine layout can be finalized, such as the calculation of the mechanical loads on each wind turbine to ensure that they are within the design limits of the wind turbine model(s)/configuration(s) of interest.
The published PCT application WO 2008092462 describes a method for designing a wind plant wherein at least one group of wind turbines within the plant are selected to produce a non-optimal output as compared to another group of wind turbines for the same wind conditions in order to achieve a more even output for the entire plant. For example, a first group of wind turbines utilized in the plant are designed to produce a maximized output in a particular wind climate. This first group is supplemented by a second group of wind turbines that is specifically designed to produce a maximal power in lower wind speeds, and thus achieve their rated power in another window of the wind spectra as compared to the first group. The goal of the design is to increase the total power output of the plant across a broader spectra of wind conditions by having groups of wind turbines with rated power outputs at different wind speeds.
The commercially available wind plant programs, and the methodology described in the WO 2008092462 publication, have the disadvantage that they view the wind plant as a single power producing unit subjected to an overall site condition, rather than a cluster of individual turbines subjected to unique wind conditions. The conventional design methodologies typically require an initial baseline layout wherein the types of turbines and overall site conditions are already established or assumed. Thus, the methodology is constrained from the very beginning. The conventional methods do not allow for consideration of the unique wind conditions experienced by each individual wind turbine within the plant, and thus do not consider that the individual turbine output can be increased by tailoring individual wind turbine characteristics, such as hub height, turbine types, and so forth, to the actual wind conditions experienced at each wind turbine location.
Therefore, what is needed is a wind plant design methodology that maximizes the plant's annual energy production (AEP) by tailoring individual turbine characteristics to differing wind conditions that are experienced through the plant.